DIFFUSION-LIMITED REACTIVE WETTING: STUDY OF SPREADING KINETICS OF Cu-Cr ALLOYS ON CARBON SUBSTRATES

摘要

Spreading kinetics of Cu-Cr alloys diluted in Cr on smooth vitreous carbon substrates are stu- died by the "transferred drop" variant of the sessile drop technique under high vacuum. In this system, the transition from large, non-wetting, contact angles to low-wetting contact angles is due to the formation of a continuous layer of wettable chromium carbide along the liquid-solid interface. It is shown that the drop spreading rate is controlled by diffusion of the reactive atom species (Cr) from the bulk liquid to the solid- liquid-vapor triple line. Results for the dependence of spreading rate on time, drop mass, and alloy com- position are compared with the predictions of a recently published model for diffusion-limited reactive wet- ting.